The main function of the core of a wire rope is to（）.
A. give flexibility
B. support the strands laid around it
C. allow some circulation around the strands
D. allow lubrication inside the rope
What two descriptions best define DWDM？ （）
A. a WDM system that is compatible with EDFA technology
B. an optical technology for transmitting up to 16 channels over multiple fiber strands
C. an optical technology for transmitting up to 32 channels over multiple fiber strands
D. a technology for transmitting multiple optical signals using less sophisticated transceiver designthen CWDM
E. a technology for transmitting more closely packed optical signals using more sophisticatedtransceiver designs than CWDM
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